A thick plate is a material having a thickness of approximately 6 mm or more, a width of 1 to 6 m and a length of 4 to 25 m. In order to automatically measure the length and width and a camber of such a thick plate, according to the related art, a laser speedometer and an imaging device for observing a width direction are used.
The speed of material, such as a thick plate, is measured using a speedometer and is integrated according to time so as to measure a length of the material, and images are taken using an imaging device for each predetermined length measured in this way and then the images are connected to one another so that a width and a camber of the material can be measured.
Related inventions include Korean Patent Registration No. 10-0685039 (published on Feb. 13, 2007) by the present applicant, entitled as ‘apparatus and method for measuring length of a steel plate’.
Referring to FIG. 1, in the apparatus and method for measuring the length of the steel plate, while the steel plate is moved, a tail end of the steel plate is provided between two metal detectors 31 and 32 provided at an entry side of the steel plate, and in the instance that a front end of the steel plate is detected by another metal detector, images at the tail end of the steel plate can be taken using a camera 39.
A length of the steel plate between the two metal detectors 31 and 32 is calculated using the images at the tail end of the steel plate, and a distance between a second metal detector 32 and a metal detector that detects the front end of the steel plate is added to the calculated length of the steel plate so that the length of the steel plate can be finally calculated.
It is not possible to use the above-mentioned technology in calculation of a length of a thick-plate wide-width material including two sheets.
Referring to FIG. 2, two sheets of a thick-plate wide-width material may be moved parallel to each other based on a traveling direction of the thick-plate wide-width material.
However, because the thick-plate wide-width material can be cut into two sheets in the previous process line thereof and then can be moved at a long distance by a transfer roller, one of the two sheets of the thick-plate wide-width material can be firstly moved.
Thus, a position difference between a front-end portion and a tail-end portion of the two sheets of the thick-plate wide-width material may occur. When a front-end portion of one steel plate is detected and then images are taken at a tail-end portion thereof so as to measure a distance between the front-end portion and the tail-end portion of the one steel plate, like in the technology described in the apparatus and method for measuring the length of the steel plate, a length of each of the two sheets cannot be measured.
In particular, in the apparatus and method for measuring the length of the steel plate, metal detectors are used. Thus, it is difficult to measure dimensions, such as a width and a camber of material.